Examiner



a. commas? i comma 0R Prism Patented Jan. 10, 1928.

UNITED STATES PATENT OFFICE.

HOWARD F. WEISS AND RALPH FORBUSH BY IESNE ASSIGNMENTS, T0

SIGNORS,

NORRIS, OF MADISON, WISCONSIN, AS- C. F. BURGESS LABORATORIES, INC., OF

WALL BOARD.

R0 Drawing.

The present invention relates to wall boards suitable for use on thewalls or cellings of a room and having good heat insulating ua-lities.It is made from a mixture of a fil er and a binder which pufi's into aporous rigid coherent mass under the' action of heat and is providedwith a facing of other material. It is an object of the presentinvention to produce a molded product composed for the most part ofinorganic material, that product being light in weight, cheap in cost,and having a high porosity, and, consequently, a low thermalconductivity. The wall boards of the present invention may be of thethickness and of the size of ordinary paper wall boards, and have afacing of paper on one or both sides. This sheet material can be putbetween the studding of a building to serve in place of back plaster. Itcan also be used in sheets or blocks to form a wall or ceiling overwhich a layer of plaster or hard finish can be applied. Similarly it maybe used as the exposed surface of the wall, and before or afterattachment to the studding may be decorated with enamel, paint,calcimine, or the like, applied directly to the mineral sheet, orapplied to the paper facing or facings.

As set forth in a copending application, Serial No. 7 520,511, filedJune 17, 1924, when an intumescent binder such as a soluble alkalisilicate, hide glue or cornstarch is mixed with a filler and subjectedto the action of heat, the mass expands or puffs up and ultimatelyhardcns into a firm strong body filled with air cells or pores. the sizeand distribution of which we find can to a large extent be. controlled.Unless the expansion or pufling of the materialis restricted as in aclosed inold or form. the expansion is likely to proceed so far that theresultant product will be too light and {)rothy to accomplish the endsnow desired y us. I

The density and the physical characteris tics of wall boards made fromsuch material by the application of heat in a mold will depend in parton'the relative percentages of binder and filler; in part on the sizeofthe moltbwith respect to -theamount of raw Application filed June 17,1824. Serial No. 720,510.

material put in for heat treatment, and in part on the chemical andphysical characteristicsof the filler. By suitable control of thesefactors, and of the temperature and duration of heat treatment, a widerange may be obtained in the physical characteristics of the product.

Various fillers can be used, such, for exzmple, ascrulslhedldololinitle, limestone, blast urnace or ot er s ag, ao in, sate asbestos eit s or owder arious clays, ag wool, pow ere s1 ica,ochre, tripoli, olcanic ash, pggnice, kieselgu'hr, ashes, or various1nixtnre s t.hereof.

Instead of using a filler that is entirely, of mineral origin, there maybe incorporated in the mixture beforeheattreatment thereof, organicmaterials, such-a 1r, wood pul fcurkfsawdust, charcoal, .SVOOfl slivers,or shredded barkT"Such organic materials may be used to alter theproperties to the degree desired. For certaln purposes the filler may beentirely of organic origin.

By way of illustration we ive below detailed instructions for procee ingin accord- :nce with the method of the present invenion.

An alkali silicate, such as sodium silicate, having a density of about425 B. is intimately mixed as in a mixer with a filler to form a doughhaving a consistency about' like that of putty. The amount of fillervaries with its character, for example in using dolomite the fillerconstitutes about of the weight of the wet mix, while in usingkieselguhr or sifted coal ashes, the filler constitutes only 20% of theweight of the wet mix. When the board or panel is to have a paper facingon both sides, the dough or m1x thus formed is spread upon a sheet ofpaper either 'in an even layer oras strips. (an even layer having adepth of to will form a board approximately in thickness) A second sheetof paper. is .placed'on top of the dough so that the product in itsgreen condition consists of} two sheets or strips of paper with a:layer. of doughbetween. The paper we havebeen' using is an ordinary chipboard rather heavily sized so that it be water'ra istant and tough,although, of course, other kinds of paper can be used. The green sheetis then slid between two steam heated iron platens spaced a distanceequal to the thickness desired for the finished board, say, forinstance, The steam platens can be heated with steam at a pressure ofabout to 100 lbs., but a temperature of more than about 1' 0 C. shouldnot be employed to avoid charrmg of the paper facing. The application ofheat of about that temperature causes the dough to pull u and force theupper sheet of paper against t 1e upper platen. During this heatingprocess steam is driven oil from the mixture, particularly along theedges of the board. Some dough also may escape around the ed es of theboard without disadvantage. uring this heating and expanding process,and the driving oil of water from the mixture the silicate undergoes aradical physical change, and there may even be a chemical reactionbetween the silicate and the filler. In about thirty minutes the doughhas puffed sulficiently and suiticient moisture has been driven OK sothat the board in its pufied and porous condition is stifier than whenit was wet or green, although it still is somewhat plastic. The hotboard is then sli ped from between the latens and pressed tween tworigid suraces and there allowed to cool so that when it has cooled it isheld sufiiciently fiat. It is then in a stiff hardened and porouscondition, and can be trimmed with saws and cut to the desireddimensions.

If the board is to be faced with paper on one side only, a greased ironsheet is substituted for one of the paper sheets.

The tenacity with which the composition sticks to the paper sheets isone of the important characteristics of the paper faced board, for thereis no tendency for the sheets to blister or strip away from the mineralfiller. The paper is very tenaciously held, thereby strengthening theboard and adding to its resistance against chipping during shipment, orwhile nails are being driven through it into the studding. In crosssection the inorganic core of the finished board is not unlike inappearance the cross section of a loaf of fine grained bread.

\Ve have found that a soap, such s sodium resinatc, stearate and thelike, or material such as oleic acid which will be saponified by thesilicate, can be advanta eously added to the batch, for controlling t tosize and distribution of the air bubbles or cavities. For instance, witha mixture of sodium silicate and ashes in about equal parts by weightthere may be added soap to the extent of less than one-half of onepercent by 'weight. This soap addition makes the bubbles smaller, butmore numerous, and reduces the apparent density of the finished product.Presumably these holes or cavitics represent spaces where steam wastrapped in the mix during the putting procedure.

Using 2.7 parts by weight of sodium silicate of 425 B., 4.0 parts offinely ground dolomite, then mixing to a stiff dough, there may beproduced, after heat treatment, a strong product weighing 45.0 lbs. percu. ft. By increasing the proportion of dolomite a heavier product willresult. Thus by adding 6.0 parts of dolomite in the mix indicated, aproduct weighing 62 lbs. per cu. ft. may be made. It is not advantageousto make a denser product.

We have found the following batch to give excellent results, thepercentage given being parts my weight 39% 425 B. sodium silicatesolution.

58% powdered dolomite.

29% fine sawdust.

0.1% sodium oleate.

Dolomite, which consists essentially of calcium and magnesium carbonatesin varying proportions up to about and 45% respectively, is widelydistributed throughout the United States, and is available in largequantities and low cost in the State of Illinois and in neighboringStates. See Bulletin 46 of the State of Geological urvey of Illinoisentitled Lime stone resources of Illinois).

The wall board made as above described can be sawed and handled much asplaster or gypsum board is handled, and has the advantage thereover thatit is lighter in weight and far more porous. Not only is the material oflow conductivity for heat and sound, but it has a low water absorptioncoefficient and if necessary can be waterproofed.

1. A wall-board characterized by the tcnacity between the core and thefacing comprising a mixture of an intumescent binder and a filler,puffed by heat to a highly porous coherent b0 and having a facing heldin place by the intumesced binder.

2. A wall-board characterized by the tonacity between the core and thefacing comprising a mixture of an alkali silicate and a filler, pufiedby heat to a highly porous body, and having a facing held in place bythe int-umesced binder.

3. A wall-board characterized by the tenacit between the core and thefacing welg ling not more than 62% pounds per cu. ft. comprising amixture of an alkali silicate and a filler, putfed by heat, and having afacing held in place by the intumesced binder.

4. A wall-board characterized by the tenacrty between the core and thefacing comprising a mixture of an alkali silicate and a of a rouscharacter,

and having a facing held in place by the intumesced binder.

ller,fip)ufled by heat to a highly porous body i106. eoneosinoas,

, 500mm R Cross Reference EXAMINEF 5. A wall-board characterized by thetehaving a high degree of tenacity between nacity between the core andthe facing comthe core and the facing which comprises prising a mixtureof an alkali silicate and a mixing an intumescent binder with a filler,heavy mineral filler, and a porous filler, introducing the batch soformed into a mold puffed by heat to a highly porous product, having apaper lining and there heating it 7" and having a facing held in placeby the inuntil the material puffs to a porous cotumesced binder. herentproduct, and adheres to the paper.

6. A wall-board characterized by the te- 15. The process of makingwall-board nacity between the core and the facing comhaving a highdegree of tenacity between prising a mixture of sodium silicate and thecore and the facing which comprises crushed dolomite pufi'ed by heat toa highly mixing an alkali silicate with a filler, inporous product andhaving a paper facing trodncing the batch so formed into a mold held inplace by the intiunesced binder. having a paper lining and there heatingit 7 A wall-board characterized by the teuntil the material puffs to aporous coherent 13 nacity between the core and the facing eomproduct,and adheres to the paper. 50

prising a mixture of an alkali silicate, a filler, 16. The process ofmaking wall-board and a soap, pufi'ed by heat to a rigid mass, having ahigh degree of tenacity between and having an adherent facing. the coreand the facing which consists in 8. A wall-board characterized by thetemixing an alkali silicate with a filler, intronacity between the coreand the facing coinducing the batch so formed into a mold prising amixture of alkali silicate, a min lined with aper. and there heatinguntil eral filler, and sodium oleate, piifl'ed and the materia pufis toa weight less than hardened by heat, and having an adherent 62 ,4 lbs.per cu. ft. and adheres to the aper. facing, 17. The process of makingwalloard 9. A wall-board characterized by the tehaving a high degree oftenacity between nacity between the core and the facing comthe core andthe facing which consists in prising a mixture of an alkali silicate andmixing alkali silicate with a mineral filler, about 607 of a crusheddolomite based on introducing the batch so formed into a mold the wetweight of the mixture, puffed by heat lined with paper, and then heatingat about to a rigid mass, and having an adherent fac- 150 C. until thematerial puffs and harding. ens to a rigid porous mass and adheres to10. A wall-board characterized by the tethe paper. nacity between thecore and the facing com- 18. The process of making wall-board prising amixture in parts by weight of 39% having a high degree of tenacitybetween 42.5 136. sodium silicate solution, 58% powthe core and thefacing which consists in dered dolomite, 2.9% fine sawdust, 0.1%somixing an alkali silicate with a filler to diuin oleate puffed by heatto a porous body, form a batch of dough-like consistency, inand havingan adherent facing of paper. troducing the batch into a mold lined with11. The process of making wall-board paper and heating at about 150 C.for having a high degree of tenacity between about 30 minutes to puffand harden the W the core and the facing which comprises batch; andcause it to adhere to the paper. mixing an intinnescent binder with afiller, 1.9. The process of making wall-board subjecting the batch soformed to heat while having a hi h degree of tenacity between confinedbetween paper liners until the mathe core an the fac ng wh ch consistsin tcrial puffs to a porous coherent product mixing an alkali silicatewith a mineral and adheres to the paper. filler to form a batch ofdough-like consist- 12. The process of making wall board ency,introducing the batch into a mold having a high degree of tenacitybetween lined with paper and heating at about 150 the core and thefacing which comprises C. for about 30 minutes to puff and harden mixingsodium silicate with a filler, who the batch; and cause it to adhere tothe H diicing the batch so formed between paper paper. liners and thenheating by contact with hot 20. The process of making wall-board latesuntil the material pufi's to a porous having a high degree of tenacitybetween coherent product and adheres to the paper. the core and thefacing'which consists in 13. The process of making wall board intimatelymixing an alkali silicate with it having a high degrceof tenacitybetween filler and a soap, introducing the batch so the core and thefacing which comprises formed into a mold lined with paper and mixingsodium silicate with crushed doloheating to puff and harden the batch,and mite, introducing the batch so formed in a cause it to adhere to thepaper. relatively thin layer between paper liners, 21. The process whichconsists 111 ntiand then confining the material and subjectmately mixingabout 2.7 parts alkali s licate ing to heat until the material pufis toa with about 4.0 parts crushed dolomite by porous coherent product andadheres to the weight, mixing the batch to adoughy consistency,introducing it into a metal mold aper.

05 p 14. The process of making wall-board and there heating at about 150Cafor about I Rh 1 .1 i

5 the core an thirti minutes to puff and harden said being of greasedmetal, and heating to ufi doug and cause it to adhere to the having ahigh degree of tenacity between mixing an alkali silicate with a filler,in-

troducing the batch so formed into a mold lined on one face with paper,the other face aper. and harden th 22. The process of making walloard tothe paper.

e batch and cause it to ad ere 10 In testimony whereof we aflix oursigthe facing which comprises natures.

HOWARD F. WEISS. RALPH FORBUSH NORRIS.

